title: Aberrant DNA methylation at genes associated with a stem cell-like phenotype in cholangiocarcinoma tumors.
abstract: Genetic abnormalities of cholangiocarcinoma have been widely studied; however, epigenomic changes related to cholangiocarcinogenesis have been less well characterized. We have profiled the DNA methylomes of 28 primary cholangiocarcinoma and six matched adjacent normal tissues using Infinium's HumanMethylation27 BeadChips with the aim of identifying gene sets aberrantly and epigenetically regulated in this tumor type. Using a linear model for microarray data, we identified 1610 differentially methylated autosomal CpG sites, with 809 hypermethylated (representing 603 genes) and 801 hypomethylated (representing 712 genes) in cholangiocarcinoma versus adjacent normal tissues (false-discovery rate ≤ 0.05). Gene ontology and gene set enrichment analyses identified gene sets significantly associated with hypermethylation at linked CpG sites in cholangiocarcinoma including homeobox genes and target genes of PRC2, EED, SUZ12, and histone H3 trimethylation at lysine 27. We confirmed frequent hypermethylation at the homeobox genes HOXA9 and HOXD9 by bisulfite pyrosequencing in a larger cohort of cholangiocarcinoma (n = 102). Our findings indicate a key role for hypermethylation of multiple CpG sites at genes associated with a stem cell-like phenotype as a common molecular aberration in cholangiocarcinoma. These data have implications for cholangiocarcinogenesis, as well as possible novel treatment options using histone methyltransferase inhibitors.
authors.affiliation: Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand.|Liver Fluke and Cholangiocarcinoma Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand.
authors.forename: Ruethairat
authors.initials: R
authors.lastname: Sriraksa
authors.affiliation: Epigenetics Unit, Department of Surgery and Cancer, Imperial College London, IRDB Building, Hammersmith Hospital Campus, London, W12 0NN, UK.
authors.forename: Constanze
authors.initials: C
authors.lastname: Zeller
authors.affiliation: Epigenetics Unit, Department of Surgery and Cancer, Imperial College London, IRDB Building, Hammersmith Hospital Campus, London, W12 0NN, UK.
authors.forename: Wei
authors.initials: W
authors.lastname: Dai
authors.affiliation: Department of Genomics of Common Disease, School of Public Health, Burlington-Danes Building, Hammersmith Hospital Campus, London W12 0NN, UK.
authors.forename: Afshan
authors.initials: A
authors.lastname: Siddiq
authors.affiliation: Department of Genomics of Common Disease, School of Public Health, Burlington-Danes Building, Hammersmith Hospital Campus, London W12 0NN, UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Walley
authors.affiliation: Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand.|Liver Fluke and Cholangiocarcinoma Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen, 40002, Thailand.
authors.forename: Temduang
authors.initials: T
authors.lastname: Limpaiboon
authors.affiliation: Epigenetics Unit, Department of Surgery and Cancer, Imperial College London, IRDB Building, Hammersmith Hospital Campus, London, W12 0NN, UK.
authors.forename: Robert
authors.initials: R
authors.lastname: Brown
mesh_terms: D001650:Bile Duct Neoplasms / Q000235:genetics* / Q000473:pathology; D001652:Bile Ducts / Q000378:metabolism; D001653:Bile Ducts, Intrahepatic / Q000378:metabolism / Q000473:pathology*; D014408:Biomarkers, Tumor / Q000235:genetics*; D018281:Cholangiocarcinoma / Q000235:genetics* / Q000473:pathology; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000473:pathology*; D010641:Phenotype; D011401:Promoter Regions, Genetic / Q000235:genetics; D013447:Sulfites / Q000737:chemistry
chemical_list: D014408:Biomarkers, Tumor; D013447:Sulfites; C042345:hydrogen sulfite